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[#1502] Additional documentation for implicit joins

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lukaseder 2018-06-01 11:37:47 +02:00
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jOOQ-manual/src/main/resources/org/jooq/web/manual-3.11.xml
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@ -4934,6 +4934,23 @@ create.select(
<p>
The generated SQL is almost identical to the original one - there is no performance penalty to this syntax.
</p>
<h3>How it works</h3>
<p>
During the SQL generation phase, implicit join paths are replaced by generated aliases for the path's last table. The paths are translated to a join graph, which is always <code>LEFT JOIN</code>ed to the path's "root table". If two paths share a common prefix, that prefix is also shared in the join graph.
</p>
<p>
Future versions of jOOQ may choose to generate correlated subqueries or inner joins where this may seem more appropriate, if the query semantics doesn't change through that.
</p>
<h3>Known limitations</h3>
<ul>
<li>Implicit JOINs are currently only supported in <reference id="select-statement" title="SELECT statements"/> (including any type of subquery), but not in the <code>WHERE</code> clause of <reference id="update-statement" title="UPDATE statements"/> or <reference id="delete-statement" title="DELETE statements"/>, for instance.</li>
<li>Implicit JOINs can currently only be used to access columns, not to produce joins. I.e. it is not possible to write things like <code>FROM book IMPLICIT JOIN book.author</code></li>
</ul>
</html></content>
</section>